Management of Anterior Stromal Necrosis After Polymethylmethacrylate ICRS: Explantation Versus Exchange With Corneal Allogenic Intrastromal Ring Segments

PURPOSE: To evaluate management of keratoconic eyes with anterior stromal necrosis overlying the intracorneal ring seg-ment (ICRS), by either ICRS explantation alone or exchange with corneal allogenic intrastromal ring segments (CAIRS). METHODS: Among 643 Intacs SK (Additional Technology, Inc) inserted at one institutional center, 16 eyes (15 patients) with overlying spontaneous anterior stromal necrosis were identi-fied. Data included size of stromal defect and refractive and topographical findings before ICRS insertion, before anterior stromal necrosis, and 6 months after intervention. RESULTS: The 10-year incidence of anterior stromal necrosis after femtosecond laser-assisted ICRS insertion was 5.5%. Eight eyes underwent ICRS removal only and 8 eyes had ICRS exchanged with CAIRS. In the first group, CDVA worsened from 0.14 before melt to 0.28 logMAR after removal (P = .10), simulated keratometry (SimK) and maximum axial keratom-etry (Kmax) increased from 44.73 to 46.34 diopters (D) (P = .14) and from 49.23 to 52.26 D (P = .14), respectively, and comaworsened from 0.87 to 1.52 D (P = .02). In the CAIRS group, CDVA of 0.16 before melt improved to 0.11 logMAR postopera-tively (P > .99), and topographic indices stabilized with SimK, Kmax, and coma mildly altering from 45.31 to 45.44 D (P > .99), from 49.25 to 49.64 D (P > .99) and from 0.87 to 0.81 D (P > .99), respectively. Whether the ICRS were explanted or exchanged, the visual and topographic mean values were bet -ter than those reported before ICRS implantation, whereas higher order aberrations in eyes without CAIRS regressed to levels before ICRS insertion. At the site of melt, thinnest re-sidual stromal thickness averaged 327 mu m with ICRS removal and 490 mu m with CAIRS. Eyes with larger melt areas resulted in less optimal results with CAIRS implantation. CONCLUSIONS: Early experience in the management of ante-rior stromal necrosis by exchange of polymethylmethacrylate ICRS with CAIRS seems to avoid stromal thinning and confer better visual and topographic results, which were more pro-nounced with thicker segments. The benefit of CAIRS in large stromal melts needs to be investigated.